Shotgun short stroke gas system

ABSTRACT

A bolt-actuating gas system comprising an annular gas chamber, and annular piston, and an annular piston sleeve mounted on a tubular magazine wherein the piston sleeve includes a push rod for contacting the bolt assembly. The push rod contacts the bolt assembly but is not connected thereto so that when the piston is moved through its work stroke, the push rod drives against the bolt assembly to propel the latter toward its retired position. Furthermore, the bolt assembly can be manually retracted to its retired position without causing concurrent movement of the piston, sleeve and rod.

United States Patent [72] Inventor [21 Appl. No. [22] Filed [45]Patented [73] Assignee Joseph A. Badali Branford, Conn. 763,566

Sept. 30, l 968 Mar. 9, 197 l Olin Corporation [54] SHOTGUN SHORT STROKEGAS SYSTEM 5 Claims, 4 Drawing Figs.

[52] US. Cl 89/191 [51] Int. Cl F41d 5/04 [50] Field ofSearch 89/191,193, 159

[56] References Cited UNITED STATES PATENTS 2,582,989 1/1952 Harvey....89/l9lX 3,200,710 8/1965 Kelly et al 89/191 3,246,567 4/1966 Miller89/191 3,386,336 6/1968 Roy 3,420,140 1/1969 Beretta PrimaryExaminerBenjamin A. Borchelt Assistant ExaminerStephen C. BentleyAttorneys-William W. Jones, 11. Samuel Kieser, Donald R. Motsko, RichardS. Strickler, Robert H. Bachman and Thomas P. ODay ABSTRACT: Abolt-actuating gas system comprising an annular gas chamber, and annularpiston, and an annular piston sleeve mounted on a tubular magazinewherein the piston, sleeve includes a push rod for contacting the boltassembly.

The push rod contacts the bolt assembly but is not connected thereto sothat when the piston is moved through its work stroke, the push roddrives against the bolt assembly to propel the latter toward its retiredposition. Furthermore, the bolt as sembly can be manually retracted toits retired position Without causing concurrent movement of the piston,sleeve androd.

Patented March 9, 1971 2 Sheets-Sheet l INVENTOR JOSEPH A. BAD/4L!ATTORNEY Patented March 9, '1971 2 Sheets-Sheet B INVENTOR JOSEPH A.BADAL/ BY Myr a:

ATTORNIz'Y l SHOTGUN SHORT STROKE GAS SYSTEM This invention relates to ashort stroke gas system for use in actuating the bolt assembly of afirearm, such as a shotgumor the like.

Conventional gas operated shotguns have slide arms connnecting thepiston the to bolt slide so that movement of the piston results inmovement of the bolt assembly. When this type of gun is opened by hand,that is to say when the bolt assembly is manually retracted to itsretired-position, the slide arms and piston move with the bolt assembly.As the gun gets dirty from repeated use, and as deposits form in the gascylinder and'on the piston, the gun becomes more difficult to manuallyopen;

A further disadvantage attendant to conventional gas operated shotgunslies in the exposure of the elements housed in the receiver tocombustion gases when the gun is fired. As previously noted, theconventional gas operated shotgun in cludes at least one, and generallytwo slide arms which are connected to the bolt assembly and which arealso generally connected to the gas'piston. Since the gas piston ispositioned well forward on the gun, and the bolt assembly is rearward onthe gun in the receiver, the slidearms-are of considerable length. Thelength of the conventional slide arms renders them flexible and subjecttomeasurable bowing when the compressive force of the piston is appliedto one end of the slide .arms when the gun is fired. In order to permitthe slide'arms to move freely through the front wall of the of thereceiver without jamming during actuation of the action of theconventional shotgun, sizeable apertures are cut through the front wallof the receiver. While the large apertures permit the slide arms to movefreely through the front wall of the receiver, these apertures exposethe various mechanical assemblies which are housed in the receiver tocontaminated combustion gases which blow out of the gas cylinder towardthe receiver. Exposure to these combustion gases causes undesirabledeposits of material to form in the receiver, thus requiring periodiccleaning to remove these deposits.-

The gas system of this invention provides for a piston stroke which isshorter than the extent of movement of the bolt assembly duringactuation of the latter. The gas system includes an annular bracketmember mounted ,on the gun barrel and surrounding a portion of .atubular cartridge magazine to define therewith an annular gas chamber. Aring-shaped piston member is slidably mounted on the magazine anddisposed in the gas chamber, and a light weight piston sleeve member isconnected to the piston and slidably mounted on the magazine to extendtoward the receiver. A rigid push rod is connectedto the piston sleeve,the push rod extending rearward therefrom throughan aperture in thefront wall of the receiver to a position adjacent the boltassembly. Therigidity of the rod permits the rod aperture to be only slightly largerthan the outside diameter of the rod sothat a snug, sliding fit isachieved. The achievement of a snug fit between the rod and the aperturehelps in greatly reducing ;the amount of combustion gas blow blown intothe receiver. The bracket member includes lateral vents for exhaustingcombustion gases away from the receiver to further aid in reducing theamount of combustion gases blown into the receiver. A spring is mountedto bias the piston sleeve and piston toward the gas chamber. The pushrod is not connected to the bolt assembly but is positioned next to thebolt assembly so that the rod is moved against the bolt assembly duringthe work stroke of the piston to begin movement of the bolt assemblytoward its retired position after the gun is fired. The rod stops itsrearward movement at the end of the work stroke of the piston, whichoccurs when the piston sleeve strikes the front face of the receiver,but the momentum imparted .to the bolt assembly from the rod causes thebolt assembly to move rearwardly to its retired position away from therod. Thus the automatic actuation of the bolt assembly is accomplishedwithout the use of slide arms, or the like, connected to the bolt, andwith minimum exposure of the interior of the receiver to combustiongases. Also from the fact that the push rod is not connected to the boltassembly, it is readily apparent that the bolt assembly can be manuallyretracted to its retired position without causing concurrent movement ofthe piston and piston sleeve.

It is, therefore, an object of this invention to provide a gas systemfor actuation of a bolt assembly in a semiautomatic shotgun, which gassystem has a short stroke.

It is a further object of this invention to provide a gas system of thecharacter described wherein the bolt assembly is unconnected to thebolt-actuating portion of the gas system.

It is yet another object of this invention to provide a gas system ofthe character described wherein the interior of the receiver portion ofthe gun is effectively sealed against penetration of gases from the gaschamber.

Other objects, advantages and features of the invention will becomeapparent to one skilled in the art from the following detaileddescriptionwhen read in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an explodedside .view of the various components of a.preferred embodiment of the gas system of this invention;

FIG. 2 is a side elevation, partially in section, of a portion of ashotgunincluding the gas system of FIG. 1, with the bolt assembly of thegun and the various movable components of the gas system disposed intheir. normal positions prior to firing the FIG. 3 is a vertical.sectional view taken along line 3-3 of FIG. 2; and

FIG. 4 is a side elevation similar toFlG. 2, but showing the piston,piston sleeve, and push rod in their respectiverearwardmost positionswith the bolt assembly immediately prior tomovement out of contact withthe push rod.

Referring now to FIG. 1, a preferred embodiment of the gas system ofthis invention is shown. The system includesa conventional tubularmagazine 2 which is mounted in any known manner beneath and parallel tothe barrel of a shotgun. The forward end 4 of the magazine 2 is threadedto receive an end closure cap 6. "An annular bracket member 8 is mountedon the magazine 2, the bracket 8 having a first bore 10 of apredetermined smaller diameter which is snugly fitted against theoutside surface of the magazine 2 so as to form a gastight sealtherewith. The bracket 8 also includes a second bore 12 of apredetermined layer diameter which is spaced apart from the outsidesurface of the magazine 2'to define therewith a gas chamber 52 (seeFIG..2). A plurality of lateral gas vents 14 are disposed in the wall ofthe bracket 8 in communication with the second bore 12. A laterallydirected gas bleed port 16 is drilled through the wall of the bracket 8to communicate with the second bore 12 at a location adjacent to thefirst bore 10.

An annular piston-member 18 having a first smaller bore 20 and a secondlarger bore 22 is slidably mounted on the magazine 2. An oblique face 24is interposed between the bores 20 and 22, the face 24 preferably beingformed at an angle of about 30 with the vertical. A pair of raised lands26 are formed on the exterior of the piston 18 for gas sealingengagement with the larger bracket bore 12. A split ring 28 having anobliquely cut and face 30 and a normally cutface 32 is disposed withinthe piston bore 22, the face 30 being contiguous with the oblique pistonface 24.

A lightweight annular piston sleeve 34 is slidably mounted on themagazine 2 and extends into the piston bore 22 to snugly engage thepiston 18. The inner end 36 of the sleeve 34 is adjacent to the normalface 32 of the ring 28. A rigid push rod 38 is affixed to the sleeve 34as by welding, or the like, the rod 38 extending beyond the outer end ofthe sleeve 34. A compressible spring 40 is mounted on the rod 38, thespring bearing against the front wall of the receiver on one hand, andbearing against the end wall 42 of a slot 44 cut into the sleeve 34 onthe other hand.

Referring now to FIG. 2, the gas system of FIG. 1 is shown mounted on ashotgun (only partially shown). The bracket 8 is mounted below the gunbarrel 46, and a port 48 is drilled through the barrel 46 into thebarrel bore 50. The port 48 is aligned with the gas bleed port 16 toprovide a passage through which pressurized combustion gases are bledfrom the bore 50 into the gas chamber 52. It is'noted that bracket 8,piston 18, piston sleeve 34, and magazine 2 are all disposed within aforearm 54 mounted on on the barrel 46. The magazine 2 is connected inany conventional manner to the receiver 56 of the shotgun. The boltslide 58 is shown in FIG. 2

in bolt assemblys the battery position. The remaining portions of thebolt assembly are omitted for purposes of clarity, it being understoodthat the bolt may take any conventional form. It isfurther understoodthat the bolt assembly is biased by a spring (not shown) toward thebattery position in a conventional manner. The push rod 38 extendsthrough an aperture 60 in the front wall 62 of the receiver 56. The sizeof the aperture 60 has been greatly exaggerated in FIG, 2 for purposesof clarity, however, itis to be understood that the diameter of theaperture 60 is preferably only about 0.003 in.'

largerthan the diameter of the rod 38 so as to provide a snug gassealing fit. The left hand end of the rod 38, as viewed in FIG. 2, iscontiguous with the front face of the bolt slide-58. The bolt slide 58is mounted for reciprocal movement on a pair of rails 64 in the receiver56. g

' FIG. 3 shows the radial position of the various elements and themanner in which the push rod 38 contacts the'bolt slide 58. The boltslide 58 is of sufficiently large mass to serve as an inertial body tocontinue rearward movement of the bolt assembly after the initial energyis supplied by the push rod 38.

FIG. 4 shows the actuating positions of the various members of the gassystem when a shot charge is fired from the gun. The shot charge 66 isshown as his propelled down the barrel bore at a position downstream ofthe aligned gas bleed ports 16 and 48. High-pressure combustion gasesare bled through the ports 16 and 48 into' the gas chamber 52. Thesehigh pressure gases cause the piston 18 to move through the bracket bore12 toward the receiver 56, thus driving the piston sleeve 34 and rod 38.The end point of the work stroke of the piston 18 is reached when thepiston sleeve 34 strikes the front wall 62 of the receiver 56, thisposition being shown in FIG. 4. It is noted that the spring 40 iscompressed during the driving stroke of the piston 18. Movement of thepiston 18 to the end point of its work stroke uncovers the gas vents 14so as to vent the high pressure gases laterally out of the gas chamber52 to lower the pressure therein.

As the piston 18 is driven through its work stroke, the split ring 28flexes radially inwardly against the magazine 2, the tlexure resultingfrom the angular interface between the ring 28 and the piston face 24.The ring 28 thus provides a gastight seal between the piston 18 and themagazine 2, and also serves to scrape the magazine clean of any depositsduring the work stroke of the piston. On the return stroke of the piston18, the resiliency of the ring 28 causes it to flex back to its normalloose fit about the magazine 2, thus offering no impedance to thereturning of the piston to its original position.

As previously noted, the mass of the bolt slide 58 is such that the boltslide acts as an inertial body for the bolt assembly. Thus movement ofthe bolt assembly from the battery position to the position shown inFIG. 4 imparts sufficient momentum to the bolt assembly that the lattercontinues to move rearward in the receiver to its retired position, eventhough the push rod 38 ceases its rearward movement at the positionshown in FIG. 4.

When the pressure in the gas chamber 52 has been sufficiently lowered,the spring 40 acts to return the piston 18, piston sleeve 34 and rod 38to their original position (shown in FIG. 2), even as the bolt assemblycontinues its rearward movement to is its retired position.

It will be readily appreciated from the preceding that the gas system ofthis invention permits a short piston stroke, while at the same timeprovides for proper automatic actuation of the the bolt assembly of thefirearm. Furthermore, it is readily apparent that the bolt assembly in agun incorporating the' gas system of this invention can be manuallyretracted .to its retired position without concurrent movement of thepiston,

sleeve, or rod occurring. The provision of a rigid push rod and gasvents in the gas system also presents a cleanly operating assemblyhitherto unattainable in the gas systems of the prior art.

Since many changes and variations of the disclosed embodimerit ofthe-invention may be made without departing from the inventive concept,it is-not intended to limit the invention otherwise than as required bythe appended claims.

Iclaim: v

1. In a semiautomatic firearm having a receiver, a barrel secured to thereceiver, a-tubular magazine mounted adjacent and parallel to thebarrel, and a bolt assembly reciprocally mounted in the receiver, a gasoperated system for automatic reciprocation of said bolt assembly, saidsystem comprising:

a. inertia means secured to said bolt assembly and contained whollywithin said receiver;

b. bracket means secured to said barrel and surrounding a portion ofsaid magazine, said bracket means having a wall radially spaced fromsaid magazine to provide therewith a gas chamber;

0. port means interconnecting said gas chamber with a bore in saidbarrel;

d. annular piston means slidably mounted on said magazine and extendinginto said gas chamber, said piston means being movable through arelatively short work stroke and return; and

e. push means interposed between said piston means and said boltassembly and extending through an aperture in said receiver, said pushmeans being connected to said piston means and free of attachment withboth said bolt assembly and said inertia means, said push means beingoperative to move against said bolt assembly and said inertia means toinitiate reciprocation of 5 said bolt assembly when said piston means isdriven through its work stroke, and to impart sufficient energy to saidbolt assembly and said inertia means to cause the latter to continuereciprocation completely.

.2. The gas system of claim 1, further comprising spring means adjacentto said piston means and operative to move the latter and said pushmeans through said return stroke.

3. The gas system of claim 1, wherein said piston means compriseslightweight stop means operative to stop movement of said piston meansby impact with said receiver after said piston means has been driventhrough its work stroke and before said piston means completely exitssaid gas chamber, whereby a portion of said piston means always remainsin said gas chamber during said work stroke.

4. The gas system of claim 1, wherein said push means is a rigid,substantially nonbendable rod, and said receiver aperture is ofrestricted size so as to provide a substantially leakproof gas seal withsaid rod to prevent entry of blowback gases into said receiver.

5. The gas system of claim 1, wherein said bracket means comprises atleast one laterally directed vent operative to lower gas pressure insaid gas chamber after said piston means has been moved through its workstroke.

1. In a semiautomatic firearm having a receiver, a barrel secured to thereceiver, a tubular magazine mounted adjacent and parallel to thebarrel, and a bolt assembly reciprocally mounted in the receiver, a gasoperated system for automatic reciprocation of said bolt assembly, saidsystem comprising: a. inertia means secured to said bolt assembly andcontained wholly within said receiver; b. bracket means secured to saidbarrel and surrounding a portion of said magazine, said bracket meanshaving a wall radially spaced from said magazine to provide therewith agas chamber; c. port means interconnecting said gas chamber with a borein said barrel; d. annular piston means slidably mounted on saidmagazine and extending into said gas chamber, said piston means beingmovable through a relatively short work stroke and return; and e. pushmeans interposed between said piston means and said bolt assembly andextending through an aperture in said receiver, said push means beingconnected to said piston means and free of attachment with both saidbolt assembly and said inertia means, said push means being operative tomove against said bolt assembly and said inertia means to initiatereciprocation of s said bolt assembly when said piston means is driventhrough its work stroke, and to impart sufficient energy to said boltassembly and said inertia means to cause the latter to continuereciprocation completely.
 2. The gas system of claim 1, furthercomprising spring means adjacent to said piston means and operative tomove the latTer and said push means through said return stroke.
 3. Thegas system of claim 1, wherein said piston means comprises lightweightstop means operative to stop movement of said piston means by impactwith said receiver after said piston means has been driven through itswork stroke and before said piston means completely exits said gaschamber, whereby a portion of said piston means always remains in saidgas chamber during said work stroke.
 4. The gas system of claim 1,wherein said push means is a rigid, substantially nonbendable rod, andsaid receiver aperture is of restricted size so as to provide asubstantially leakproof gas seal with said rod to prevent entry ofblowback gases into said receiver.
 5. The gas system of claim 1, whereinsaid bracket means comprises at least one laterally directed ventoperative to lower gas pressure in said gas chamber after said pistonmeans has been moved through its work stroke.